Delineation of an isodicentric Y chromosome in a mosaic 45,X/46,X,idic(Y)(qter-p11.3::p11.3-qter) fetus by SRY sequencing, G-banding, FISH, SKY and study of distribution in different tissues

Clinical, cytogenetic, and molecular findings of isodicentric Y chromosomes

Background

Isodicentric Y chromosomes [idic(Y)] are one of the most common structural abnormalities of the Y chromosome. The prenatal diagnosis of isodicentric Y chromosomes is of vital importance, and the postnatal phenotypes vary widely. Therefore, we present six patients prenatally diagnosed with isodicentric Y chromosomes and review the literature concerning the genotype-phenotype correlations.

Method

The clinical materials of six patients were obtained. Cytogenetic and molecular approaches were carried out for these six patients.

Results

Isodicentric Y chromosomes were found in all sixpatients. Among them, four patients presented with a mosaic 45,X karyotype, one patient had a 46,XY cell line, and one patient was nonmosaic. Five of these six isodicentric Y chromosomes had a breakpoint in Yq11.2, and the other had a breakpoint in Yp11.3. The molecular analysis demonstrated different duplications and deletions of the Y chromosome. Finally, three patients chose to terminate the pregnancy, two patients gave birth to normal-appearing males, and one patient was lost to follow-up.

Conclusion

The incorporation of multiple cytogenetic and molecular techniques would offer a more comprehensive understanding of this structural chromosomal abnormality for genetic counselling.

Short Stature on a Boy: Mosaicism with an Isodicentric Y Chromosome

Mosaicism brings great variability into the clinical expression of numerical and structural chromosomal abnormalities. The phenotypic variability of 45,X/46,XY mosaicism extends from Turner syndrome to apparently physically normal males. We present a case of a 14-year-old adolescent with short stature and delayed puberty, who was admitted in a Paediatric Endocrinology outpatient clinic. After a careful investigation, he was found to have a 45,X/46,X,idic(Y)(p11.32) mosaicism. This case report emphasizes the wide range of etiologies that can be involved in short stature and that chromosomal study is an important tool when firstly approaching males with short stature, avoiding unnecessary tests. There is an important clinical need for gonadal follow-up in this situation and for support in the decision about sex of rearing and sex orientation, when justifiable.

A Rare Mosaic Karyotype of 45,X/46,X,psu idic(Y)(p11.32)/46,XY with SHOX Haploinsufficiency, External Male Genitalia, and Short Stature

In this case study, we describe a 3-year-old boy who was referred to the Inonu University Hospital with short stature complaint. His height was 86 cm (-2.96 SDS), weight was 12 kg (-2.43 SDS), and head circumference was 46.5 cm (-2.34 SDS). Chromosomal analyses were performed on cultured peripheral blood lymphocytes of the patient and his parents and showed the patient's karyotype mos 45,X[20]/46,X,idic(Y)(p11.32)[29]/46,XY[1]. The karyotypes of the parents were normal. Subsequently, specific FISH probes were hybridized to the related regions of the sex-determining region Y (SRY), centromere X/Y (CEP X/Y), and short stature homeobox (SHOX) genes. Simultaneous SNP array-CGH was conducted. As to our knowledge, we present the first patient with mosaic isodicentric Y chromosome with 3 different cell lines and normal male external genitalia. Our results suggest that it would be beneficial to study cytogenetic and molecular cytogenetic methods together for better diagnostic accuracy and treatment.

A de novo derivative Y chromosome (partial Yq deletion and partial duplication of Yp and Yq) in a female with disorders of sex development

We report an atypical disorders of sex development (DSD) case with no mutation of SYR gene but partial Yq deletion and partial duplication of Yp and Yq. This case emphasizes duplicated region Yp11.2→Yq11.223 with partial deletion of Yq11.223→Yqter most probably perturbed the sex differentiation and led to female phenotype.

Molecular‑cytogenetic study of de novo mosaic karyotype 45,X/46,X,i(Yq)/46,X,idic(Yq) in an azoospermic male: Case report and literature review

The present study describes a 36‑year‑old male with the 45,X/46,X,i(Yq)/46,X,idic(Yq) karyotype, who suffered from azoospermia attributed to maturation arrest of the primary spermatocyte. To the best of our knowledge, this rare karyotype has not yet been reported in the literature. The results of detailed molecular‑cytogenetic studies of isodicentric (idic)Y chromosomes and isochromosome (iso)Y, which are identified in patient with complex mosaic karyotypes, are presented. The presence of mosaicism of the three cell lines 45,X, 46,X,i(Yq) and 46,X,idic(Yq) may be a contributing factor for spermatogenic failure, in addition to the instability of iso/idic Y chromosomes to pass the spermatogenesis process. Possible mechanisms of the formation of the mosaic karyotype and karyotype‑phenotype correlations are discussed. The current study highlights that routine karyotype analysis and fluorescent in situ hybridization‑based technology are more useful in detecting mosaic chromosomal abnormality, predicting the clinical features of patients during genetic counseling and improving artificial reproductive technologies.

A case of mosaic Klinefelter syndrome associated with isodicentric Yp

We describe a case of mosaic Klinefelter syndrome demonstrating an isodicentric Y chromosome. A 70-year-old man visited our outpatient clinic complaining of dysuria resulting from atrophy of the penis. His height was 170 cm and his weight was 60 kg. A serum hormonal analysis revealed hypergonadotropic hypogonadism. A chromosomal analysis with fluorescence in situ hybridization revealed four cell lines in which the karyotypes were 47,XXY, 46,XY, 46,XX and 47,XX,idic(Y) (q11.2). To the best of our knowledge this is the first case of mosaic Klinefelter syndrome bearing an isodicentric Y chromosome. The origin of the isodicentric Y is discussed. (Reprod Med Biol 2008; 7: 177-180).